1. Field of the Invention
This invention relates to an apparatus for continuously manufacturing a slide fastener chain, in which lengths of a fastener tape (referred to merely as a tape hereafter) are introduced into a synthetic resin injection molding machine. The tape in this case has perforated sections of predetermined length consisting of holes provided beforehand along a longitudinal edge of the tape, the holes serving to secure fastener elements to be subsequently injection-molded therein, and solid sections where no holes have been provided. The injection molding machine includes molds provided with rows of fastener element molding cavities that agree with the holes in the perforated sections of the tape. To continuously manufacture the slide fastener chain, the apparatus of the invention repeats the steps of introducing a perforated section of the tape into the molds of the molding machine, injection molding and securing fastener elements onto the tape at each of the holes in said perforated section, and then feeding the next perforated section of the tape into the molds, the last mentioned perforated section being separated from the earlier perforated section by the interval of a solid section. More particularly, the present invention concerns a fastener chain manufacturing apparatus with an improved tape feed device having a tensioning mechanism for stretching the tape. Specifically, the holes in the perforated sections of predetermined length are spaced at regular intervals which are smaller than the intervals at which the fastener element molding cavities in the molds are spaced. When the molds are half-closed just prior to the injection molding step, the tensioning mechanism tensions the tape to stretch it by a predetermined amount, whereby the spacing intervals and positions of the holes in the tape are brought into agreement with the spacing intervals and positions of the fastener element molding cavities in the molds.
2. Description of the Prior Art
The inventor has already invented an apparatus for manufacturing a continuous length of slide fastener chain and has filed an application on such invention under the date of Oct. 1, 1979 (Japanese Patent Public Disclosure No. 51326/81, corresponding to U.S. Ser. No. 190,979, now Pat. No. 4,336,220). The apparatus introduces a tape, provided in advance with a continuous row of holes along a longitudinal edge thereof, but without solid sections devoid of the holes, into a synthetic resin injection molding machine for molding the fastener elements, tensions the tape to stretch it, and when the molds are half-closed, in such a manner that the spacing intervals and positions of the holes in the tape are brought into agreement with the spacing intervals and positions of the fastener element molding cavities, then closes the molds to injection-mold and secure fastener elements onto the tape at the holes. These steps are repeated to manufacture the fastener chain. The earlier invention, however, provides a length of slide fastener chain in which the fastener elements are molded and secured onto the tape in a continuous row, and cannot be applied, as such, to the manufacture of a fixed length of slide fasteners provided with alternating sections having attached fastener elements, and blank sections devoid of fastener elements.